1. Field of the Invention
This invention relates to an apparatus for transmitting and receiving optical signals which can be used in, for example, a wireless communication network.
2. Description the Related Art
In a wired LAN (local area network), terminal devices are connected to each other via wires. The terminal devices can communicate with each other via the wires.
It is known to combine a wired LAN and a wireless communication network. For example, a wired LAN is additionally provided with an access point device (a gateway device) which can execute both wired communication and wireless communication. The access point device is connected via wires to normal terminal devices in the wired LAN. The access point device can communicate with the normal terminal devices in the wired LAN via the wires. Also, the access point device can execute wireless communication with terminal devices in a wireless communication network. In this case, the wired LAN and the wireless communication network are connected via the access point device (the gateway device). In addition, the access point device is a member of the wired LAN as well as a member of the wireless communication network.
According to an example of the wireless communication network, the access point device (the gateway device) and the terminal devices can communicate with each other by using optical signals such as infrared-light signals.
Japanese patent laid open number (Japanese published unexamined patent application) 8-139675 discloses an optical transmitting and receiving apparatus which is used in an optical communication network. The apparatus in Japanese patent laid open number 8-139675 includes a light transmitting and receiving unit which has a light transmitting mirror and a light receiving mirror coaxial with each other. The light transmitting and receiving unit can be rotated about a vertical axis and also about a horizontal axis. The rotation of the light transmitting and receiving unit enables its optical axis to be accorded with an optical axis of a communication opposite party.
Japanese patent laid open number 8-139675 also discloses a light transmitting and receiving unit which has a light transmitting mirror and a light receiving mirror arranged side by side along a vertical direction.